Last line indicator for typewriters



Dec. 27, 1955 w, GAMBLE 2,728,440

LAST LINE )TNDICATOR FOR TYPEWRITERS Filed Aug. 2, 1951 INVENTOR.

WILLIAM GAMBLE BYW Z United States My invention consists of a device which indicates to a typist that the predetermined top of the bottom margin of a sheet of paper is approaching the line of type of the typewriter.

The object of this invention is to provide such a device that is easily and economically operable in connec tion with the different-sized platens found on different typewriters.

This object is attained through the use of a mark which is located on the platen knob of the typewriter.

The properties of this mark, and the various positions of the platen knob with respect to this mark, are described following the description of the drawing.

Referring to the drawing, Figure l is a perspective rear view of that portion of a typewriter which includes the platen knob 1, which is directly attached to the platen axle 2, both parts being revoluble with the platen 3, which is located in front of the rear feed-roll 4. A certain kind of a mark is shown located on the platen knob.

Figure 2 is a front perspective view of the easily identifiable platen, platen axle, and platen knob, and with the addition of a line 6 located in the middle of the front side of the platen. This line represents the line of type of the typewriter, the line of type being the point at which the printing characters of the typewriter strike the platen while the typist is typing. The mark 7 is a variation of the mark 5 shown in Figure 1.

The position of the mark when the paper is introduced into the machine is hereafter called the beginning position, and the position of the mark when the last line, or top of the bottom margin, is reached and the paper is removed from the machine is called the end position. The end position of the mark is always located at the apex of the platen knob.

The exact position of the beginning position of the mark is determined by inserting a sheet of paper into a typewriter, said paper having a mark indicating the top of the bottom margin that hereafter will be desired on all subsequent sheets of paper of the same size. This mark on the paper is used solely on the sheet of paper which is being used to determine the beginning position atent of the platen knob mark, and subsequent sheets of paper used in the typewriter for the purpose of being typed on will have no position-indicating marks of any kind whatsoever.

After the paper with the mark indicating the top of the bottom margin of -the sheet of paper is introduced into the typewriter, the platen knob is revolved so that the mark on the paper indicating the last line coincides with the line of type 6 of the typewriter. When this relationship is established, the platen knob mark is adjusted to the apex of the periphery of the platen knob. The paper is then rotated around the platen in the reverse direction in which paper is normally revolved until the top edge of the paper is discharged from the rear feed-roll, at which time the position of the mark on the periphery of the platen knob is noted, for hereafter this position will be the beginning position of the mark, and the mark will be in this position hereafter when other papers of the same length are introduced into the typewriter.

Since the platen knob of a typewriter does not revolve smoothly, but jumps from one graduated slot to another, said slots in pica-type machines being one-sixth of an inch apart, the typist is capable of setting the beginning position of the mark in exactly the same position each time a sheet of paper is introduced into the typewriter; likewise, the end position of the mark is capable of being exactly determined also.

The mark is used as hereinafter described in order to warn the typist of the approach of the top of the bottom margin to the line of type.

The mark is set in the beginning position, and the paper is inserted into the machine. While the typewriter is being operated, each return of the carriage will move the indicating mark circularly around the platen knob. When the typist gets down to within four inches of the top of the bottom margin on his paper, he can see at any time the location of the mark on the platen knob, and since the end position of the mark is always located at the top of the platen knob, the distance between the location of the mark and the end position of the mark shows how much space is left in which to type,

Having described my invention, I claim:

1. In a typewriter having a platen and a platen knob, a last line indicator consisting of a single mark applied to the side face of the platen knob, said mark being readily visible to the operator at all times during a revolution of the platen knob.

2. In a typewriter having a platen and a platen knob, a last line indicator consisting of an angular mark applied to the platen knob, one branch of said angular mark extending across the periphery of the platen knob while its other branch extends radially inwardly from said periphery along one side face of the platen knob, said mark being readily visible to the operator at all times during a revolution of the platen knob.

References Cited in the file of this patent UNITED STATES PATENTS 

